Control mechanism

ABSTRACT

A cam body, movable both axially and laterally, is so shaped and positioned relative to cam followers that the total possible response thereof to movements of the cam body may be at any instant, (1) regulated from a maximum to zero, (2) proportioned as desired to secondary devices operated by the followers, and (3) subdivided into constant-proportion components of response metered to each of such devices.

United States Patent McCullough [1 1 3,655,148 51 Apr. 11, 1972 [5CONTROL MECHANISM [72] Inventor: Edward E. McCullough, Brigham City,

Utah

[73] Assignee: Thiokol Chemical Corporation, Bristol, Pa. [22] Filed:June 20, 1969 [21] Appl. No.: 839,780

[52] U.S. Cl ..244/3.22, 137/636.1 [51] Int. Cl ..F4lg 7/00 [58] FieldofSearch 4/110; 137/82, 83; 244/] SA,

[56] References Cited UNITED STATES PATENTS 2,402,027 6/1946 Crowther..74/ l 10 2,923,315 2/1960 Bletcher et al 1 37/636,] 3,221,760 12/1965Buchanan 137/82 3,511,103 5/1970 Cox, Jr. ..74/l 10 3,515,170 6/1970Mullaly 137/636. 1

Primary Examiner-Verlin R. Pendegrass Attorney-Edward E. McCullough [57] ABSTRACT A cam body, movable both axially and laterally, is so shapedand positioned relative to cam followers that the total possibleresponse thereof to movements of the cam body may be at any instant, (I)regulated from a maximum to zero, (2) proportioned as desired tosecondary devices operated by the followers, and (3) subdivided intoconstant-proportion components of response metered to each of suchdevices.

7 Claims, 7 Drawing Figures Patented April 11, 1972 2 Sheets-Sheet 1FIG. 3

FIG. 2

INVENTOR. EDWARD E. McCULLOUGH AGENT Patented April 11, 1972 3,655,148

2 Sheets-Sheet 2 INVENTOR. EDWARD E MCCULLOUGH AGENT CONTROL MECHANISMBACKGROUND OF THE INVENTION This invention relates to controls; and,more particularly, it relates to controls capable of automaticallyproportioning components of some quantity (as of fluid or electriccurrent) for proportionate operation of secondary devices. The inventionherein described was made in the course of or under a contract with theUS. Air Force.

There are a number of applications wherein a total of some quantity offluid, etc., at any given instant must be metered proportionately to twoor more secondary devices. Examples of this requirement are found insystems for steering rockets wherein a quantity of fluid is distributedto two or more ports through which it may be injected into the rocketnozzle or into small secondary motors to provide side forces on therocket. This is ordinarily accomplished by individual valves operatedremotely, resulting in a very complex system tending towardinefiiciency.

SUMMARY OF THE INVENTION The present invention is a compact, unifiedcontrol wherein cam followers capable of operating such secondarydevices are arranged in contact with surfaces of a cam body such thatmovement thereof automatically imparts to each cam follower theappropriate amount of motion to produce the required effect in asecondary device operated thereby.

An object of the invention is to provide a lightweight, compact, unifiedcontrol for proportioning components of some quantity to secondarydevices.

Another object of the invention is to provide such a control wherein thetotal possible response to be proportioned to secondary devices may beany quantity thereof from a maximum to zero.

Another object of the invention is to meter components of some quantityin constant proportions to each secondary device.

Another object of the invention is to meter fluids, etc., to secondarydevices with a greater degree of precision than has heretofore beenpossible.

Other objects and advantages of the invention will become apparent as itis disclosed in the following detailed description and accompanyingdrawings, wherein identical characters designate the same partsthroughout the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a central, longitudinal section of a preferred embodiment ofthe invention;

FIG. 2 is a transverse section taken on line 2-2 of FIG. 1;

FIG. 3 is a top view of the invention;

FIG. 4 is a line diagram showing how the cam followers of FIG. 1 metercomponents of an effect in constant proportions; FIG. 5 is a transversesection taken on line 5-5 of FIG. 1;

FIG. 6 is a longitudinal section of a second embodiment of theinvention; and

FIG. 7 is a longitudinal section of a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of theinvention, shown in FIGS. 1 through 5, has a housing 10 having the shapeof a hollow, truncated pyramid l1 intersecting a hollow cuboid form 13.A cam body 12 positioned within the housing 10 has bearing surfaces 14and convergent cam surfaces 16. The small end 18 of the cam body 12 isgimbaled at 20 to a guide block 22, so that it cannot rotate about thelongitudinal axis of the control 24 relative to the guide block 22. Theguide block 22 fits into the cuboid portion 13 of the housing 10 foraxial sliding move ment therein so that the guide block 22 cannot rotaterelative to the housing 10. Although the guide block 22 and the interiorof the portion of housing 10 into which it fits are both of rectangularcross section, it is obvious that they would function equally well if ofany noncircular cross section. The guide block 22 may be moved in axialdirections by some actuation means, here represented by an actuation arm26 threadedly engaged to the guide block 22 and attached to the pistonof a fluid-operated cylinder not shown. The cam body 12 may be moved inlateral directions by opposing, fluid-operated actuators 28 mounted onthe base of the pyramidal portion 11 of the housing 10. A plurality ofU-shaped, resilient tubes 30a and 30b are mounted in the housing 10 sothat the bend portions 32 thereof are in contact with the cam surfaces16 of the cam body 12 and the open-end portions 34 penetrate the wallsof the housing 10 for communication with some secondary devices. Hencethe sides of the tubes 30a and 3012 that are in contact with the camsurfaces 16 respond to movements of the cam body 12 in the manner of camfollowers to change the cross-sectional forms of the tubes at their bendportions 32. In the application shown, the secondary devices are small,liquidfuel, vernier reaction motors 36, used for steering a rocket notshown. In practice, they would be arranged circumferentially about thebase of the rocket and outwardly directed. One of these motors 36 isshown schematically in FIG. 1. Fuel and oxidizer lines, represented bybroken lines 38, connect a conventional fuel injector 40 of the motor 36with the tubes 30a and 30b. Levers 42, pivoted at 44 to the guide block22, normally rest on the walls of the pyramidal portion 11 of thehousing 10, with the bend portions 32 of the tubes 30a and 30b beingconfined between the levers 42 and the cam surfaces 16 of the cam body12.

In the embodiment shown, the relative sizes of the tubes 30a and 30b areselected to admit passage therethrough of the desired proportions offuel and oxidizer. If, for example, these sizes are selected so that thequantity of oxidizer flowing through tubes 300 should be four times asgreat as the quantity of fuel flowing through tubes 301;, it can be seenthat this proportion will remain substantially constant regardless oflateral or axial movements of the cam body 12. This results from thefact that cross-sectional areas of the tubes 30a and 30b are alwaysapproximately similar figures, from a geometrical point of view (seeFIG. 4). If lines 46 and 48 in the plane of the cam surface 16 and thesurface of the lever 42, respectively, between which a given set oftubes 30a and 3017 are confined, are extended to intersection as shown(the point of intersection being the center of rotation for thecam-surface line 46), then the minor axes 50 and 52 of the ellipses 54and 56 representing the cross-sectional areas of the tubes become sidesof similar triangles, and, hence, are always proportional. Also, sincesmall, proportional adjustments are also made in the lengths of themajor axes 58 and 60 because of constant circumferences of the ellipses54 and 56, it can be said that the cross sectional areas of the tubes30a and 30b are always proportional at the bend portions 32, admittingfuel and oxidizer therethrough in constant proportions.

In the extreme open and laterally neutral position of the cam body 12,as shown in FIG. 1, the tubes 30a and 30b are all half closed so that,when the cam body 12 is moved into an extreme lateral position, thetubes 30a and 30b on one side thereof will be completely closed whilethose on the opposite side will be completely open. The cam body 12never loses aetual contact with any of the tubes 30a and 3011. If suchloss of contact were permitted, the total quantity of propellant beingdelivered to the complete set of motors 36 would be changed withouteffecting the desired proportional thrust of one motor 36 relative toits diametrically, opposite counterpart. When the guide block 22 ismoved away from the cam followers (tubes 30a and 30b), the levers 42 areforced away from the walls of the housing 10 by the shoulders 62 at theintersection of the pyramidal and cuboid portions of the housing 10 sothat they close all tubes 30a and 30b to the extent that the guide block22 is moved. In this way the total amount of fuel delivered to thecomplete set of motors 36 may be varied from a maximum to zero, whilepermitting the instantaneous total to be metered proportionally to theindividual motors 36. At

the same time, the constant proportion of fuel to oxidizer metered toany given motor 36 is never altered.

FIG. 6 shows a manually-operable version of the invention, which may beused in a manner identical to that of FIG. 1, and for the same purposes,except that the actuators 28 and the axial actuation arm 26 are replacedby a handle 64 attached to one end of the cam body. To provide greaterease of control, a compression spring 66 is confined between the guideblock 22 and the small, closed end of the housing 10'. The spring 66maintains the tubes 30a and 30b in a normally open position untilopposing force is exerted by an operator on the handle 64. An endclosure 68, having an aperture 70 through which the handle 64 projects,is press fitted to the housing 10'. The aperture 70 is large enough toallow the cam body 12 to close any set of tubes 30a and 30b when lateralpressure is exerted by an operator on the handle 64. This embodiment ofthe invention is particularly well adapted for use as a control in amanned space capsule or other jet-propelled vehicle.

A third embodiment of the invention is shown in FIG. 7. This embodimentoperates in a manner similar to that of FIG. 1, and is similarlyconstructed, except that the cam followers are not pinch valves. Thetubes 30a and 30b and the levers 42 of FIG. 1 are here replaced by rods72, slidably mounted at 74 in the sides of the housing 10'. All otherparts are identical to those of the embodiment shown in FIG. 1. This isa particularly versatile form of the invention, since the rods 72 can beused to operate any of a variety of secondary devices, such aspotentiometers, valves, fluid actuators, etc. The primary objective,however, is the same as that for the other two embodiments of theinvention, i.e., that the totality of a given quantity (of fluid,electric current, etc) may be selectively proportioned among individualones of a plurality of secondary devices, that this totality may bevaried from a maximum to zero, and that separate components of thatquantity may be metered to each of the secondary devices in constantproportions regardless of how the total is distributed. This lastproperty may be derived if the rods 72 are used in pairs as are thetubes 30a and 30b in FIG. 1. It is obvious that both tubes and rods maybe pluralized beyond sets of two, if there are more than two componentsof the total effect to be metered out in constant proportions to eachsecondary device. The relative response of each rod 72 of a set isdetermined by its position with respect to the center of rotation of thecam body 12.

An invention has been described herein which provides a compact andversatile control for a number of useful applications. Although it hasbeen set forth with considerable specificity regarding detail, it isnoted that such details may be altered without departing from the scopeof the invention. For example, the guide means for the cam body 12,shown in FIG. 1 as comprising the noncircular guide block 22 attached bygimbal to the cam body 12 and slidably fitted into a noncircular portionof the housing 10, could be replaced by equivalent mechanisms, such as(I) keying the actuation arm 26 to the fluid actuator to which it isconnected, to prevent rotation thereof (in which case the only functionof the guide block 22 would be for mounting the levers 42), and (2)fitting crossbars to the ends of the arms of actuators 28 so that thecrossbars bear against the bearing surfaces 14 and extend laterally,whereby rotation of the cam body 12 about the axis of motion of guideblock 22 would be prevented.

The invention claimed is:

l. A control mechanism comprising:

a housing;

a cam body having convergent cam surfaces and positioned within thehousing for both lateral and axial movement therein;

a noncircular guide block that fits into a portion of the housing foraxial sliding movement therein, that portion of the housing beingappropriately shaped to fit the guide block;

a gimbal connecting the guide block to the cam body to prevent rotationthereof about the axis of the housing;

' cam followers mounted in the housing, and in contact with theconvergent cam surfaces of the cam body) for response to movementsthereof, the cam followers e mg in sets of at least two for each camsurface and the cam followers of each set being arranged in tandem fromthe gimbal, whereby they may represent constant-proportion components ofeach output; and

actuation means mounted on the housing and operatively in contact withthe cam body for moving it axially and laterally relative to thehousing.

2. The control mechanism of claim 1 wherein the cam followers are sidesof resilient tubes, so that, responsive to movement of the cam body, thecross-sectional area of at least a portion of each tube will be changedin size, thereby altering the quantities of any fluid passing throughthe tubes.

3. The control mechanism of claim 2 wherein a set of more than one ofsaid tubes having selected diameters is responsive to the same camsurface; and further including a lever hinged to the cam body so thatthe tubes are confined between the lever and the cam surface; and ashoulder fixed into the housing in contact with the lever, so that axialmotion of said cam body may cause the shoulder to act as a fulcrum tomove the lever relative to the cam body and thereby vary the openness ofthe tubes to a degree corresponding to the extent that the cam body ismoved, whereby the cross-sectional area of each tube of the set ismaintained in constant proportion to those of the other tubes responsiveto the same cam surface.

4. The control mechanism of claim I wherein the cam followers are rodsslidably mounted in the housing for operating secondary devices.

5. The control mechanism of claim 1 wherein a set of cam followers arerods responsive to the same cam surface, relative response of each rodof the set to movements of the cam body being determined by its positionwith respect to the center of rotation for the cam body.

6. The control mechanism of claim 1 wherein the actuation meanscomprises a double-acting, fluid-operated actuator fixed to the housingand attached to the cam body for axial movement thereof, and a pluralityof fluid-operated actuators mounted on the housing circumferentiallyabout said cam body and in contact therewith for lateral movementthereof.

7. The control mechanism of claim 1 wherein the actuation meanscomprises a handle fixed to the cam body, and spring means bearingagainst the cam body and the housing, biasing the cam body away from oneend thereof so that force exerted on the handle is opposed by the springmeans, and the housing has an aperture, through which the handle mayextend, large enough to permit lateral movement of the handle but notlarge enough to permit passage of the cam body therethrough.

1. A control mechanism comprising: a housing; a cam body havingconvergent cam surfaces and positioned within the housing for bothlateral and axial movement therein; a noncircular guide block that fitsinto a portion of the housing for axial sliding movement therein, thatportion of the housing being appropriately shaped to fit the guideblock; a gimbal connecting the guide block to the cam body to preventrotation thereof about the axis of the housing; cam followers mounted inthe housing, and in contact with the convergent cam surfaces of the cambody for response to movements thereof, the cam followers being in setsof at least two for each cam surface and the cam followers of each setbeing arranged in tandem from the gimbal, whereby they may representconstant-proportion components of each output; and actuation meansmounted on the housing and operatively in contact with the cam body formoving it axially and laterally relative to the housing.
 2. The controlmechanism of claim 1 wherein the cam followers are sides of resilienttubes, so that, responsive to movement of the cam body, thecross-sectional area of at least a portion of each tube will be changedin size, thereby altering the quantities of any fluid passing throughthe tubes.
 3. The control mechanism of claim 2 wherein a set of morethan one of said tubes having selected diameters is responsive to thesame cam surface; and further including a lever hinged to the cam bodyso that the tubes are confined between the lever and the cam surface;and a shoulder fixed into the housing in contact with the lever, so thataxial motion of said cam body may cause the shoulder to act as a fulcrumto move the lever relative to the cam body and thereby vary the opennessof the tubes to a degree corresponding to the extent that the cam bodyis moved, whereby the cross-sectional area of each tube of the set ismaintained in constant proportion to those of the other tubes responsiveto the same cam surface.
 4. The control mechanism of claim 1 wherein thecam followers are rods slidably mounted in the housing for operatingsecondary devices.
 5. The control mechanism of claim 1 wherein a set ofcam followers are rods responsive to the same cam surface, relativeresponse of each rod of the set to movements of the cam body beingdetermined by its position with respect to the center of rotation forthe cam body.
 6. The control mechanism of claim 1 wherein the actuationmeans comprises a double-acting, fluid-operated actuator fixed to thehousing and attached to the cam body for axial movement thereof, and aplurality of fluid-operated actuators mounted on the housingcircumferentially about said cam body and in contact therewith forlateral movement thereof.
 7. The control mechanism of claim 1 whereinthe actuation means comprises a handle fixed to the cam body, and springmeans bearing against the cam body and the housing, biasing the cam bodyaway from one end thereof so that force exerted on the handle is opposedby the spring means, and the housing has an aperture, through which thehAndle may extend, large enough to permit lateral movement of the handlebut not large enough to permit passage of the cam body therethrough.